/Engine/Source/Editor/UnrealEd/Classes/Animation/DebugSkelMeshComponent.h
Extended viewport text delegate handling. Registering a delegate allows external objects to place custom text in the anim tools viewports.
[FDelegateHandle](API\Runtime\Core\Delegates\FDelegateHandle) RegisterExtendedViewportTextDelegate ( const FGetExtendedViewportText & InDelegate )